What are the risks and challenges of SSH multiplexing and tunneling in different environments and networks?

1 SSH multiplexing

SSH multiplexing allows you to reuse an existing SSH connection to establish multiple sessions without re-authenticating every time, which can save time, bandwidth, and CPU resources, as well as reduce the risk of exposing credentials or keys. However, this method can make your connection less stable and more prone to errors or timeouts, especially if you have a large number of sessions or a low-quality network. Additionally, it can increase the attack surface and the potential damage if your master connection is compromised or hijacked by an adversary. Furthermore, it can make your connection harder to monitor and troubleshoot as you may not be able to see or control the individual sessions or their parameters. Consequently, you should use SSH multiplexing with caution and only when you trust the server and the network, and when you need to perform multiple tasks that require the same credentials and settings.

2 SSH tunneling

SSH tunneling allows you to establish a secure and encrypted channel between your local and remote machines, allowing for the forwarding of any type of traffic, such as TCP, UDP, or X11. This can enable access to services or resources that may otherwise be blocked, restricted, or inaccessible due to firewalls, proxies, or censorship. However, SSH tunneling can lead to performance and reliability issues due to added overhead and latency. It may also violate policies and regulations of your organization, ISP, or destination country, thus creating legal or ethical issues. Additionally, it can create security risks by bypassing or weakening security measures in place to protect your network or data and exposing your traffic to interception or manipulation by malicious SSH servers or compromised networks. Therefore, you should use SSH tunneling with caution and only when you have a legitimate and authorized reason to do so, trusting the SSH server and the network while encrypting and authenticating your traffic properly.

3 Best practices

To use SSH multiplexing and tunneling safely and effectively, there are some best practices you should follow. Ensure that your passwords or keys are strong and unique, and change them regularly. SSH agent forwarding or proxy commands can help to avoid storing or exposing your keys on remote servers. Additionally, SSH configuration files or aliases can help to simplify and standardize your SSH commands and parameters. To limit or control the duration, number, or type of your multiplexed or tunneled sessions, you can use SSH options or tools. Finally, SSH logging or auditing can be used to monitor and record your SSH activity and detect any anomalies or breaches. By adhering to these best practices, you can take advantage of the benefits of SSH multiplexing and tunneling while reducing the risks and challenges they present in various environments and networks.

4 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?